Reproduce the claim

“Empty messages are delivered” sounds specific enough to fix. The title names a behavior, and the body asks for a regression test. But the issue is still a claim, not evidence that the bug exists.

Issue claim → smallest probe → observed result

The Investigator tests the premise against the repository before writing a specification.

Make the Issue Prove Itself

Create a read-only Investigator that reproduces or contradicts a reported bug inside Vercel Sandbox.

Hands-on Exercise 3.1

Connect the live services

The first two sections stayed local. Live investigation needs a repository connector and Vercel Sandboxes.

Link the directory. eve link creates or selects the Vercel project and pulls local OIDC credentials used by AI Gateway and Vercel Connect:

pnpm exec eve link

Create a managed GitHub connector, install its GitHub App on your course repository only, and attach it to the linked project:

vercel connect create github --name signalworks-factory --triggers
vercel connect attach github/signalworks-factory --triggers --trigger-path /eve/v1/github
vercel connect list

If vercel connect is unavailable, update the CLI. The connector supplies short-lived installation tokens; do not create a personal access token or GitHub App key.

Add the course configuration to the linked project, then pull it locally:

vercel env add FACTORY_REPO --value YOUR_GITHUB_NAME/signalworks-software-factory
vercel env add FACTORY_LABEL --value factory
vercel env add FACTORY_BRANCH_PREFIX --value factory/
vercel env add FACTORY_SETUP_COMMAND --value "pnpm install --frozen-lockfile"
vercel env add GITHUB_CONNECTOR --value github/signalworks-factory
vercel env pull .env.local

Confirm the five values. GITHUB_CONNECTOR must match vercel connect list, and FACTORY_REPO must name the connected personal repository. Refresh expired authentication with vercel env pull .env.local.

Build the Investigator

Open agent/lib/config.ts and set the fallback repository to your personal GitHub fork. Vercel Hobby projects use repositories owned by your personal account.

Create agent/subagents/investigator/sandbox.ts:

import { defineSandbox } from "eve/sandbox";
import { vercel } from "eve/sandbox/vercel";
import {
  repoBootstrap,
  repoOnSession,
  repoRevalidationKey,
} from "../../lib/github/repo-sandbox.js";
 
export default defineSandbox({
  backend: vercel(),
  bootstrap: repoBootstrap,
  onSession: repoOnSession,
  revalidationKey: repoRevalidationKey,
});

The sandbox clones into /workspace/repo, isolated from the host filesystem.

Create agent/subagents/investigator/agent.ts with a small first contract:

import { defineAgent } from "eve";
import { MODELS } from "../../lib/models.js";
 
export default defineAgent({
  description:
    "Investigate a reported behavior against the real repository. Reproduce the claim and return command-backed evidence. Never modify files.",
  model: MODELS.investigator,
  outputSchema: {
    additionalProperties: false,
    properties: {
      claimSupported: { type: "boolean" },
      evidence: {
        items: {
          additionalProperties: false,
          properties: {
            command: { type: ["string", "null"] },
            result: { type: "string" },
            summary: { type: "string" },
          },
          required: ["summary", "command", "result"],
          type: "object",
        },
        minItems: 1,
        type: "array",
      },
    },
    required: ["claimSupported", "evidence"],
    type: "object",
  },
});

Add agent/subagents/investigator/instructions.md. Require the smallest disposable probe that can decide the claim, relevant output for every command, and cleanup before returning. The Investigator never edits product files.

Finally, add the bug-lane delegation to agent/instructions.md. Pass the complete work order because specialists do not inherit the root conversation.

Try It

Check discovery first:

pnpm typecheck
pnpm exec eve info

The application should report one subagent. Then invoke the factory with the uppercase-channel fixture. This is the course's canonical non-interactive invocation command:

pnpm exec eve invoke "$(cat fixtures/issues/bug-example.md)"

eve invoke runs without the TUI using the linked environment. For an interactive trace, run pnpm exec eve dev and paste the fixture into the TUI.

The Investigator's result must include a command that demonstrates SLACK failing before the fix. A summary without a command is another claim.

Now repeat with the false-premise fixture:

pnpm exec eve invoke "$(cat fixtures/issues/false-premise-example.md)"

Both reports may enter the bug lane, but their claimSupported values should differ after the probes run.

Commit

git add agent/subagents/investigator agent/instructions.md agent/lib/config.ts
git commit -m "feat(factory): reproduce issue claims"

Done-When

• eve discovers one Investigator subagent
• The linked project has an attached GitHub connector and the five course values
• The Investigator works inside /workspace/repo
• Every conclusion contains command-backed evidence
• Disposable probes are removed before the result returns
• The real bug and false premise produce different support decisions

One report now fails before any Builder sees it. Supported observations can move on to a specification.

Solution

agent/subagents/investigator/instructions.md contains:

# Investigator
 
You investigate one work order against the repository at `/workspace/repo`. You never edit product files.
 
Read the source issue, classification, route, and existing evidence from the delegation message. For a bug, create and run the smallest disposable probe that proves or disproves the report. Remove the probe before finishing.
 
Return evidence for every conclusion. Commands include their relevant output. Observations name the file and behavior inspected. Do not claim that a bug exists without a reproducing result.

The root instructions delegate only the bug and public API lanes to investigator, passing the complete current work order.